This invention relates generally to injection molding and more particularly to a nozzle having electric slab or plate heaters which provide heat according to a predetermined profile.
Plate heaters are well known in the injection molding field, but recently most nozzles are made with a helical heating element extending around the central melt bore. For instance, the applicant's U.S. Pat. No. 4,795,337 which issued Jan. 3, 1989 discloses a nozzle in which an electric heating element is integrally brazed in a spiral channel extending around the central melt bore. One of the advantages of helical heating elements over these previous plate heaters for nozzles has been that the heat can be distributed over the length of the nozzle according to a predetermined profile by spacing the coils of the heating element as required.